MOLTEN SALT INDUCED CORROSION may be encountered whenever molten salts contact metallic or ceramic surfaces at elevated temperatures. There are numerous industrial processes in which such conditions can develop. For example, during combustion, deposits such as Na2SO4 can accumulate on hardware and cause corrosion. The combustion may occur, for example, in gas turbines, incinerators, or in diesel engines. The conditions are such that the deposits form as a thin (∼1 μm) liquid layer separating the alloy from the gas phase. There are also other industrial processes, such as molten carbonate fuel cells, where molten salts are held in metallic or ceramic containers at elevated temperatures. The molten salts can corrode the container materials, but the conditions differ from the combustion environments because the amount of salt is very large with much larger diffusion distances between the gas phase and the container material. Because of the complexity of the environments, no tests have been developed that find general acceptance. In this section, testing in molten salts present as thin layers and as deep melts will be discussed, using illustrative examples to show some of the tests that have been developed.